Hearing device with embedded channel

ABSTRACT

A hearing device having at least one of an acoustical/electrical converter and an electrical/acoustical converter respectively with an acoustical input or output. The input or output, as the case may be, is linked to a coupling opening at the outer surface of the device via a channel. At least a part of the outer surface of the device is formed by a one-part shell. The shell defines an inner space of the device, with the channel being provided within and along the part of the shell and being formed within the material of the shell.

This invention relates to an custom-moulded ear-plug deviceincorporating at least one acousto-electric converter and/or at leastone electro-acoustic converter, each with an acoustic input or,respectively, output, said input or output being connected by way of anacoustic conductor to a coupling port on the outer surface of thecustom-moulded ear-plug shell.

In custom-moulded ear-plug devices of the type mentioned, and especiallyhearing aids, whether in-ear or outer-ear hearing aids, it is commonpractice to connect the acoustic inputs to acousto-electric inputconverters or microphones and/or to connect the acoustic outputs fromelectro-acoustic output converters or speakers, via acoustic conductorelements for instance in the form of small tubes, to coupling ports onthe outer surface of the custom-moulded ear-plug shell, unless theseinputs or outputs are situated directly in the surface region of theshell in question. There are certain disadvantageous aspects to thisapproach:

The geometric position and orientation of the coupling port on the outersurface of the custom-moulded ear-plug shell relative to the inputconverters is primarily dictated by the desired acoustic receptioncharacteristics. The distance and the location of such coupling portswithin the configuration of the custom-moulded ear-plug device such as ahearing aid are co-determinators of the acoustic receptioncharacteristics. Similarly, the location of a coupling port on theoutput side of an output converter is determined, inter alia, by therelative position of the custom-moulded ear-plug device in the earcanal, and of the tympanic membrane or ear drum.

In the case of an outer-ear hearing aid in which for instance anadditional tubular, acoustic conductor extends from the outer surface ofthe custom-moulded ear-plug device into the ear canal, theaforementioned coupling port must be so positioned that the said,additional acoustic conductor can be routed in optimal fashion along thepinna and then into the ear canal. If the location of the coupling portis dictated by parameters of the type mentioned above, it will benecessary to integrate in the custom-moulded ear-plug device one orseveral converters within the confines of the physical space availableand to connect them to the coupling ports via the acoustic conductorsmentioned above. Considering the fact that in active custom-mouldedear-plug devices of that type, such as the hearing aids mentioned, thespace available for accommodating converters and other functionalelectronic elements including the battery is extremely limited, it isobvious why as often as not it takes an effort to keep the couplingports in the desired location and at the same integrate the convertersand acoustic conductors in the custom-moulded ear-plug device in amanner which optimizes both space utilization and acoustic properties.

It is the objective of this invention to remedy these shortcomings byintroducing an custom-moulded ear-plug device of the type mentionedwhich, however, offers a high level of flexibility in physicallypositioning the converters needed within the custom-moulded ear-plugdevice, largely independent of the location of the coupling ports andthus without having to pay particular attention to the spacerequirements of additional acoustic conductors that may be necessary.This is intended to make it possible to flexibly install the convertersmentioned in whatever is the optimal location within the most compactdesign possible, independent of the location of the coupling ports onthe outer surface of the custom-moulded ear-plug shell and withouthaving to take into account as restrictive factors the acousticconnecting lines or any resulting bulkiness of the device. In thecustom-moulded ear-plug device discussed, this is accomplished in thatthe acoustic conductor extends through, and is bounded by, the materialof the custom-moulded ear-plug shell.

In other words, the said acoustic conductor is integrally molded intothe custom-moulded ear-plug device, i.e. its shell. Since thecustom-moulded ear-plug device must in any event be provided with ashell with a particular wall thickness, the acoustic conductors leadingto the coupling port or ports will take up only a negligible amount ofspace in the custom-moulded ear-plug device and they can be routedessentially from and to any desired point. Where necessary, it is alsopossible at least over partial sections to combine several acousticconductors or channels as parallel signal carriers. For example, aregion of the custom-moulded ear-plug device in which there is notenough space for a channel of the desired cross-sectional size, can bebypassed or circumvented by two or more signal-carrying parallelchannels of a smaller diameter. The original channel is split intobranch channels which are recombined at the end of the size-limitedsegment.

In a preferred embodiment, the channel(s) mentioned features varyingcross-sectional sizes and shapes in different segments over its entirelength so as to optimize the acoustic transmission properties. Thiscreates a network of acoustic impedances along the channel, permittingoptimal acoustic adaptation.

In another embodiment, the impedance tuning can be obtained by means ofat least one matching stub line which extends into the channel. Forbridging greater distances in the custom-moulded ear-plug deviceaccording to this invention between the above-mentioned converter andthe coupling port it is proposed that this minimum of one channel berouted, at least over a substantial part of its length, essentiallyparallel to the outer surface of the custom-moulded ear-plug device.

While the custom-moulded ear-plug device according to this invention canbe easily designed as part of an earphone, the proposed concept isparticularly suitable for hearing aids.

If the hearing aid is designed as an in-ear hearing aid, it is furtherproposed that the channel be made part of an ear-drum venting system.This is feasible due in particular to the impedance-tuning possibilitiesreferred to above.

The following explains this invention by a description of designexamples with the aid of drawings in which:

FIG. 1 is a simplified schematic illustration of a production system,operating by the preferred process for the optimized industrialmanufacture of custom-moulded ear-plug devices;

FIG. 2 is an illustration, analogous to that in FIG. 1, of anothersystem layout;

FIG. 3 is an illustration, analogous to those in FIGS. 1 and 2, of yetanother system configuration;

FIG. 4 schematically shows an in-ear hearing aid with a conventionallymounted cerumen shield;

FIG. 5 is an illustration, analogous to that in FIG. 4, of an in-earhearing aid with an integrally molded-in cerumen shield;

FIG. 6 is an in-ear hearing aid with a conventionally machined ventinggroove;

FIG. 7( a) to (f) are partial, perspective illustrations ofcustom-moulded ear-plug shell surfaces with novel venting grooves;

FIG. 8 is a partial, schematic illustration of an custom-mouldedear-plug shell surface with varying cross-sectional sizes and shapes;

FIG. 9 schematically shows an in-ear custom-moulded ear-plug device withan extended venting groove;

FIG. 10 is an illustration, analogous to that in FIG. 9, of an in-earcustom-moulded ear-plug device with multiple venting grooves;

FIG. 11( a) to (e) show parts of custom-moulded ear-plug shells providedwith venting channels of mutually different cross-sectional shapes anddimensions;

FIG. 12 is an illustration, analogous to that in FIG. 8, of a ventingchannel in an custom-moulded ear-plug shell, featuring over its lengthvarying cross-sectional shapes and dimensions;

FIG. 13 is a schematic illustration, analogous to that in FIG. 9, of anin-ear custom-moulded ear-plug device with a machined, extended ventingchannel;

FIG. 14 is an illustration, analogous to that in FIG. 10, of an in-earcustom-moulded ear-plug device per this invention with multiple ventingchannels;

FIG. 15 schematically shows a longitudinal section of an in-earcustom-moulded ear-plug device with a ribbed interior surface;

FIG. 16 is a partial cross-sectional view of the custom-moulded ear-plugdevice per FIG. 15, with the ribs featuring mutually differentcross-sectional dimensions;

FIG. 17 is a partial perspective view of an custom-moulded ear-plugshell with interior ribbing per FIG. 15 or 16, said ribs featuring overtheir length different cross-sectional shapes and dimensions;

FIG. 18 is an illustration, analogous to that in FIG. 15, of an in-earcustom-moulded ear-plug device with external ribbing;

FIG. 19 schematically shows part of an custom-moulded ear-plug shell,ribbed per FIG. 18, with ribs of mutually different cross-sectionaldimensions;

FIG. 20 is a schematic, cross-sectional view of an custom-mouldedear-plug device with exterior ribbing and possibly interior ribbing aswell as an inner space filled at least in part with a filler material;

FIG. 21 is a schematic, partial view of a longitudinal section of ancustom-moulded ear-plug shell with a flexible and resilientlycompressible region;

FIG. 22 schematically shows a longitudinal section of an in-earcustom-moulded ear-plug device with a cavity for accommodating anelectronic module;

FIG. 23 shows the custom-moulded ear-plug device per FIG. 22 beingslipped over an electronic module;

FIG. 24 is a perspective, schematic illustration of an in-earcustom-moulded ear-plug device, in particular as employed in an in-earhearing aid, with a two-part, separable and joinable custom-mouldedear-plug shell;

FIG. 25 is a partial, schematic illustration of the integration per thisinvention of acoustic conductors and adapters connecting to anacousto-electric or electro-acoustic converter in an custom-mouldedear-plug device;

FIG. 26 is an illustration, analogous to that in FIG. 25, of thepositioning per this invention of two or more acoustic conductors in theshell of an custom-moulded ear-plug device; and

FIG. 27 is a simplified signal-flow/functional block diagram of a novelprocess, and a novel device for its implementation, whereby thecontouring of the custom-moulded ear-plug device is adapted to thedynamic movement of the area of application.

The custom-moulded ear-plug-unit design versions discussed following thedescription of the production process are preferably all manufactured bythe said production process.

DEFINITION

The term custom-moulded ear-plug device refers to a unit which isapplied directly outside the pinna and/or at the pinna and/or in theauditory meatus or ear canal. It includes external or pinnal hearingaids, in-ear hearing aids, headphones, noise- and water-blocking earplugs, and the like.

1. Production Process

In the preferred production process for fabricating the custom-mouldedear-plug devices described in detail further below, the shape of aparticular region in which an custom-moulded ear-plug unit is to beapplied, is digitized in three dimensions, whereupon the custom-mouldedear-plug unit or its shell is built up by an additive process. Additiveor incremental building i.e. composite structuring processes are alsoknown as Rapid Prototyping. For incremental processes of this nature,already employed in rapid prototyping, reference is made to:

-   -   http://ltk.hut.fi/-koukka/RP/rptree.html (1)        or to    -   Wohlers Report 2000, Rapid Prototyping & Tooling State of the        Industry (2)

The different incremental processes currently known and employed inrapid prototyping indicate that laser sintering, laser or stereolithography or the thermojet process are particularly well suited to thebuilding of custom-moulded ear-plugs or their shells and especially thespecific configurations described below. These preferred additivestructuring processes are therefore briefly summarized as follows:

-   -   Laser sintering: A thin layer of hot-melting powder is applied        on a powder bed for instance by means of a roller. A laser beam,        controlled by the 3D data of the specific individual application        area, solidifies the powder layer that corresponds to a slice or        sectional layer of the custom-moulded ear-plug unit or shell. A        solid sectional layer of the custom-moulded ear-plug unit or        shell is thus produced in the otherwise loose powder. That layer        is then lowered out of the powder deposition plane and a new        powder layer is superposed, laser-solidified to constitute        another sectional layer, etc.

-   Laser or Stereo Lithography: A first sectional layer of the    custom-moulded ear-plug unit or shell is solidified on the surface    of a liquid photopolymer by means of a UV laser. The hardened layer    is dipped and again covered with the liquid polymer. By means of the    UV laser the second sectional layer of the custom-moulded ear-plug    unit or shell is solidified on the first hardened layer.

-   The positional movement of the laser is itself controlled by the 3D    data of the specific application area previously digitized.    -   Thermojet Process: The contouring for a given sectional layer of        the custom-moulded ear-plug unit or shell follows a principle        similar to that of an ink jet printer, in that liquid is applied        based on the digitized 3D data especially of the specific area        of application. The sectional image deposited is then allowed to        solidify. Again following the principle of an incremental        buildup, layer upon layer is deposited in building the        custom-moulded ear-plug unit or shell.

Relative to additive structuring processes, including theabove-mentioned preferred process, reference is made to these otherpublications:

-   -   http://www.padtinc.com/srv_rpm_sis.html (3)    -   “Selective Laser Sintering (SLS) of Ceramics”, Muskesh Agarwala        et al., presented at the Solid Freeform Fabrication Symposium,        Austin, Tex., August 1999 (4)    -   http://www.caip.rutgers.edu/RP_Library/process.html (5)    -   http://www.biba.uni-bremen.delgroupslrp/lom.html, or        http://www.biba.uni-bremen.delgroupslrp/rp_intro.html (6)    -   Donald Klosterman et al., “Direct Fabrication of Polymer        Composite Structures with Curved LOM”, Solid Freeform        Fabrication Symposium, University of Texas at Austin, August        1999 (7)    -   a http://lff.me.utexas.edu/sis.html (8)    -   http://www.padtinc.com/srv_rpm_sla.html (9)    -   http://www.cs.hut.fi/˜ado/rp/rp.html (10)

Thus, the basic principle employed in the incremental-buildup oradditive-structuring process consists in the deposition of a thin layerof material on a surface, whether that is a full-surfaced blank as inlaser sintering or in stereo lithography, or, as in the thermojetprocess, already a contoured section of the custom-moulded ear-plug unitor shell that is being constructed. The desired sectional shape is thenstabilized, i.e. hardened.

Once a layer has hardened, a new layer is deposited on it as describedabove, hardened and bonded to the finished layer underneath. In thatfashion, layer by layer, the custom-moulded ear-plug unit or shell iscomposed by the successive, additive deposition of multiple layers.

In commercial production, the preferred method is not to separatelydeposit and solidify each individual sectional layer for a singlespecific custom-moulded ear-plug unit or shell, one at a time, but tosimultaneously produce several layers for each unit. For example, inlaser sintering one laser, typically mirror-controlled, solidifies thesectional layers of several custom-moulded ear-plug units or shellsbefore all hardened sectional layers are jointly dipped. Thereupon,after a new powder layer has been deposited on all hardened and dippedsectional layers, the next multiple sectional layers are formed.Although fabricated in parallel, the individual custom-moulded ear-plugunits or their shells are produced as separate units under appropriatedigital control.

The solidification of multiple sectional layers employs either a singlelaser beam or more than one laser beam operated and controlled inparallel.

In an alternative process, a sectional layer is individually solidifiedby a laser while concurrently a powder layer is deposited for forminganother custom-moulded ear-plug unit or shell. Subsequently that samelaser is used to solidify the prepared powder layer representing thesectional layer for the next custom-moulded ear-plug element, while thepreviously solidified layer is dipped and a new powder layer isdeposited on it. In this case the laser alternates intermittentlybetween two or several custom-moulded ear-plug units or shells which arebeing fabricated, while the idle time of the laser otherwise occurringduring the powder deposition for the forming of one of the shells isutilized for the solidification of a sectional layer of anothercustom-moulded ear-plug unit that is being built.

FIG. 1 is a schematic illustration of one process variant in which, bylaser sintering or laser or stereo lithography, several custom-mouldedear-plug units or their shells are commercially manufactured in aparallel process. The laser with its control unit 5 and its beam 3 islocated above the bed of powder or fluid material. In its position 1 itsolidifies the layer S₁ of a first custom-moulded ear-plug unit or shellunder the control of the first discrete data set D₁. Thereupon, arepositioning device 7 moves it into a second position where, under thecontrol of the second discrete data set D₂, it produces the layer S₂following another specific contour. Of course, several of the lasers maybe moved in unison, for the simultaneous production of more than oneindividual custom-moulded ear-plug layer. Not until the appropriatelasers 5, in all their predefined positions, have produced the variousindividual layers in the laser sintering process will a new powder layerbe deposited by the powder feed system 9 or, in the case of laser orstereo lithography, will the solidified layers S be dipped in the fluidbed.

As shown in FIG. 2, several individually controlled lasers 5, operatingin parallel, simultaneously solidify layers of individual custom-mouldedear-plug units or shells in one or more fluid or powder beds 1. Again,upon completion of this solidification phase and deactivation of thelasers, the powder feed unit 9 deposits a new powder layer, while in thecase of laser or stereo lithography the layers just solidified or thealready hardened structures are dipped in the fluid bed.

As shown in FIG. 3, the laser 5 solidifies the layer S₁ in one powder orfluid bed 1 a, then moves over to bed 1 b (dotted line) where, duringthe solidification phase at bed 1 a, the powder deposition device 9 bapplies powder on a previously solidified layer S₁. or, in the case oflaser or stereo lithography, the layer S₁ is dipped. Not until the laser5 is activated at bed 1 b will the powder feed unit 9 a deposit a newpowder layer at bed 1 a on the layer S₁ just solidified, or will thelayer S₁ be dipped in the fluid bed 1 a.

When employing the thermojet process, and for correspondingly increasedproductivity, sectional layers are simultaneously deposited for morethan one custom-moulded ear-plug unit or shell, essentially in onesingle stroke by one applicator head or by several such heads operatingin parallel.

The process described makes it possible to produce custom-mouldedear-plug units or shells of highly complex shapes both in terms of theirouter contours and, in the case of a shell, of its inner contours, withindividualized adaptation to the area of application concerned. Ledges,recesses and protrusions can be easily configured.

There also exist materials for the incremental build-up process whichcan be shaped into an elastic yet sturdy shell which latter, if desired,can vary in thickness down to an extremely thin yet break-resistantwall.

In a currently preferred implementation the digitizing of the specificindividual areas of application, especially those for a hearing aid andin particular for an in-ear hearing aid, is performed at a specializedinstitution, in the latter case by an audiologist. The individual imageinformation in the form of digital 3D data, especially those for hearingaids, is transmitted to a production center either on a disk or via theInternet. The production center then fabricates the individualcustom-moulded ear-plug unit or shell, in the case discussed an in-earhearing-aid shell, employing in particular the above-mentioned process.The center preferably also performs the complete assembly of the hearingaid with the appropriate functional components.

Due to the fact that, as mentioned above, the thermoplastic materialsemployed generally allow for a relatively elastic outer contour with asnug fit, the problem of pressure points in the shaping ofcustom-moulded ear-plug units or shells is far less critical than hasbeen the case in the past, a point of particular significance for in-earcustom-moulded ear-plugs. It follows that in-ear custom-mouldedear-plugs such as hearing aids, headphones, water-blocking devices andespecially in-ear hearing aids can be inserted much like elastic plugswhose surface adapts itself with a snug fit to the area of applicationi.e. the auditory meatus or ear canal. One or several venting channelscan be easily provided in the in-ear custom-moulded ear-plug unit,ensuring that, notwithstanding the resulting, perhaps relatively tightfit of the custom-moulded ear-plug unit in the ear canal, the air flowto the ear drum remains uninhibited. In the production process, thespecific 3D data for the area of application can also be mostadvantageously employed for optimizing the inner configuration of theplastic unit, even including the accommodation and constellation of anycustomized components as in the case of a hearing aid.

Specifically for custom-moulded ear-plugs in the form of hearing aids,centralized shell production also allows for the centralized storing andmanagement of individual patient data both with regard to thepatient-specific area of application and to the individual functionalelements and their settings. If for whatever reason a shell must bereplaced, it can be reproduced simply by retrieving the individual datasets, without requiring a laborious new fitting as in the past.

Given that processes for producing custom-moulded ear-plug devices,albeit prototypes only, have been part of prior art and have beendescribed in earlier literature, there is no need at this juncture torepeat all the technical details of these processes.

In any event, it has been surprising to find that adopting theseprior-art prototyping technologies yields rather substantial benefitsfor the industrial, commercially attractive production of custom-mouldedear-plugs, for reasons which for all practical purposes are of nosignificance in prototyping, such as the elasticity of suitablethermoplastic materials, the ability to customize extremely thin-walledelements, etc.

To summarize, employing the above-mentioned additive, incrementalbuild-up process in the production of custom-moulded ear-plug units orshells makes it possible to integrate in these various functionalelements, the configuration of which is already laid out in the computerduring the design phase of the custom-moulded ear-plug unit and whichare installed as the custom-moulded ear-plug unit or shell is produced.In the past, such functional elements were typically retrofitted oradded to the finished custom-moulded ear-plug unit or shell, asevidenced by seams at junctions of different or inhomogeneous materialsat the points of assembly.

For the custom-moulded ear-plugs discussed and especially thosecontaining electronic components, such as hearing aids and especiallyin-ear hearing aids, the components which can be integrated directlyinto the custom-moulded ear-plug shell by the technique proposedinclude, by way of example, the following:

Component mounts and holders, cerumen-protection systems, ventingchannels in the case of in-ear custom-moulded ear-plugs, or channellocks which keep in-ear custom-moulded ear-plugs in place in theauditory canal.

FIG. 4 schematically illustrates an example of an in-ear custom-mouldedear-plug unit 11 such as an in-ear hearing aid whose acoustic port 13 onthe ear-drum side is provided with a cerumen-protection cap 15. In pastproduction processes, such a protective cap 15 would be mounted as aseparate part on the shelf 16 of the custom-moulded ear-plug unit 11 andfastened for instance with glue or by welding. When employing theaforementioned additive build-up process, as shown in an identicalillustration in FIG. 5, the cerumen protection cap 15 a is integrateddirectly into the shell 16 a of the otherwise identical in-earcustom-moulded ear-plug unit 11 a. At the junctions, schematicallyidentified as P in FIG. 4, conventional processes would necessarily leadto material inhomogeneities or seams whereas in the case depicted inFIG. 5 there is no such seam and the material of the shell 16 ahomogeneously transitions into that of the cerumen-protection cap 15 a.

This is only one example of how conventional cerumen-protection systemsand other functional elements can be directly integrated by employingthe abovementioned production process.

The following will introduce a few specific, novel custom-mouldedear-plug devices:

2. Vented Inner-Ear Custom-Moulded Ear-Plugs

It is a conventional practice in the case of in-ear custom-mouldedear-plugs and especially in-ear hearing aids to provide a venting grooveon the outer surface, as schematically illustrated in FIG. 6. Ascurrently used venting grooves go, they are by no means optimized withregard to various features:

-   -   Acoustic properties: Prior-art venting grooves are not really        adapted to the different acoustic requirements. For example, in        active custom-moulded ear-plug devices such as in-ear hearing        aids they contribute next to nothing to an effective solution of        the feedback problem between the electromechanical output        converter and the acoustoelectric input converter. In passive        in-ear custom-moulded ear-plugs such as ear protectors, they do        not provide the desired level of protection while at the same        time maintaining good venting properties.    -   Susceptibility to cerumen: The venting grooves currently        provided on the outer surfaces of in-ear custom-moulded        ear-plugs are extremely susceptible to the formation of cerumen.

Depending on its intensity, cerum buildup can quickly limit theair-conducting capacity of the venting grooves by constricting or evenfully clogging them.

The following describes proposed venting solutions for in-earcustom-moulded ear-plugs and especially for in-ear hearing aids orear-protection devices, but also for custom-moulded ear-plugs which onlypartly protrude into the ear canal, such as headphones, which solutionseliminate at least in part the above-mentioned shortcomings ofconventional provisions.

In this context, one differentiates between venting systems which

-   -   are essentially in the form of a groove which at least in part        opens up toward the wall of the ear canal,    -   are channels completely closed toward the wall of the ear canal.        2a) Venting Systems which are Open Toward the Wall of the Ear        Canal

In FIGS. 7( a) to (f) the perspective, schematic partial illustrationsof the outer wall 18 of in-ear custom-moulded ear-plugs, resting againstthe ear canal, depict sections of innovative venting-channelconfigurations. In FIG. 7( a), the cross section of the venting groove20 a is square or rectangular with precisely defined and maintaineddimensional parameters. In FIG. 7( b) the venting groove 20 b has across section in the form of a circular or elliptic sector, again with aprecisely defined lateral curvature 21 b. Such precise definition andimplementation of the cross-sectional shape of the venting grooves 20already allows for a certain predictability and control of the acousticpropagation characteristics along the groove when that is in flushcontact with the inner wall of the ear canal. Of course, the acousticproperties also depend on the length over which the groove 20 extendsalong the outer surface 18 of the custom-moulded ear-plug unit.

FIG. 7( c) to (f) illustrate other venting-channel cross sections,additionally provided with cerumen protection. The groove per FIG. 7( c)has a T-shaped cross section.

In relation to the wide cross-sectional base of the groove in FIG. 27(c), the cantilevering of the sides 23 c and resultant narrowing 25 c inthe direction of the ear-canal wall already provides an appreciablemeasure of cerumen protection. Even if cerumen penetrates into thenarrow part 25 c and hardens there, it will not cause any substantialconstriction, never mind clogging, of the venting groove, but will onlymake it an enclosed venting channel. Following the principle explainedin relation to FIG. 7( c), FIGS. 7( d) to 7(f) show the widecross-sectional base 27 d to 27 f of the venting groove in variousshapes, such as a circular or elliptic sector per FIG. 7( d), triangularas in FIG. 7( e), or circular or elliptical as per FIG. 7( f).

A specific, precise design of the cross-sectional surface of the groove,as illustrated by way of only a few examples in FIG. 7( a) to 7(f),already leads to acoustic as well as cerum-protection properties whichare measurably superior to those of conventional, more or lessrandom-shaped venting grooves. For the desired cerumen-protection andacoustic properties, the cross sections are first computer-modeled andthen precisely integrated into the custom-moulded ear-plug productionunits. A particularly suitable way to accomplish this is to employ theadditive build-up processes explained above. Further optimization of theacoustic properties of the venting groove can be obtained by providingalong these novel venting grooves any given acoustic impedances; in FIG.8, for example, this results in venting grooves 29 which along theirlongitudinal direction feature progressively changing cross-sectionalshapes, selected and sequenced in FIG. 8 from cross-sections in FIG. 7.

In a manner similar to the design of passive electrical circuitry, theventing groove that is in contact with the ear canal can becomputer-modelled and tested for its acoustic transmission propertiesand then integrated into the in-ear custom-moulded ear-plug device orshell.

As illustrated in FIG. 8 at point A, it is possible to specificallyprovide multiple cerumen-protected sections in correspondingly exposedlocations.

It may also be altogether desirable especially with a view to optimizedacoustic properties to make the venting grooves longer than wouldnormally correspond to the basic length of a given in-ear custom-mouldedear-plug unit. As shown in FIG. 9, this is accomplished by cuttinggrooves 31 with shapes for instance as illustrated in FIGS. 7 and 8 intothe surface of the custom-moulded ear-plug unit along predefined curves,as depicted in the example of FIG. 9, practically in the form of helicalgrooves surrounding the custom-moulded ear-plug unit. Enhanced, optimaldesign flexibility is obtained by providing not only one but severalventing grooves on the surface of the custom-moulded ear-plug unit, asschematically illustrated in FIG. 10. This substantial measure of designflexibility makes it possible to configure and variably dimension theventing grooves on the surface of the custom-moulded ear-plug unit so asto optimize cerumen protection and acoustic transmission properties forany particular area of application in the ear canal.

2b) Venting Systems with Fully Integrated Channels

This design variation of the innovative venting systems consists ofventing channels which are at least in some sections fully integratedinto the custom-moulded ear-plug unit and closed off against the wall ofthe ear canal. A system of this type, designed into an custom-mouldedear-plug shell, is described below. However, it should be stressed that,if no further modules need to be integrated in the custom-mouldedear-plug unit discussed and if the latter is a solid plastic body, thefollowing statements naturally also apply to any desired routing ofchannels through the solid plastic body in question.

Analogous to FIG. 7, FIG. 11 illustrates various cross-sectional shapesand surface distribution patterns of the proposed venting channels 33 ato 33 e. In FIG. 11( a) the venting channel 33 a integrated into thecustom-moulded ear-plug shell 35 a has a rectangular or square crosssection, in the design version per FIG. 11( b) the cross section of thechannel 33 b is in the form of a circular or elliptic sector. In thedesign variant per FIG. 11( c) the cross section of the venting channel33 c is circular or elliptic while in the design variant per FIG. 11( d)it is triangular.

In the embodiment per FIG. 11( e) the custom-moulded ear-plug shellfeatures a complex interior shape, for instance with an integratedretaining-strip extension 37. For optimal space utilization the crosssection of the associated venting channel 35 e is so designed as to takeadvantage even of complex shape variations of the custom-mouldedear-plug shell. Accordingly, part of its equally complex cross-sectionalform runs into the retaining strip 37 extending from the shell 35 e.

Going back to the design variant per chapter 2a) it should be mentionedthat this type of complex cross-section which offers optimal utilizationof the available space can equally well be chosen for venting groovesthat are open toward the wall of the ear canal and, conversely, thechannel patterns illustrated in FIGS. 9 and 10 for open grooves can beused for closed venting channels as well.

FIG. 12 finally illustrates a design version of a fully integratedventing channel 39 which in its longitudinal direction, for instance inthe depicted custom-moulded ear-plug shell 41, features varying crosssections and/or cross-sectional dimensions so that, with differentacoustic impedance elements, the acoustic transmission properties can beoptimized. In this context, and with reference to chapter 5) below, itshould also be pointed out that the ability to produce complex acousticimpedance characteristics makes it entirely possible to simultaneouslyutilize at least certain sections of the venting channels, andespecially of the closed designs discussed here, as acoustic conductoroutput sections of active electromechanical converters, like on theoutput side of microphones, for instance in the case of in-ear hearingaids.

Analogous to FIGS. 9 and 10, FIGS. 13 and 14 show how in a givencustom-moulded ear-plug unit 43 the integrated venting channelsexplained in this chapter can be extended by appropriate routing, and,respectively, how two or more of these channels can be integrated intothe custom-moulded ear-plug unit, perhaps with different and/or varyingchannel cross sections analogous to FIG. 12.

These capabilities, described in chapters 2a and 2b and combinable inany desired fashion, open up to the expert innumerable design-variationopportunities for the novel venting systems and most of all, in view ofthe various and variously dimensionable parameters, considerable leewayin providing for each individual custom-moulded ear-plug unit optimalcerumen protection as well as optimal acoustic transmission properties.For all design variants the specific individualized system configurationis preferably calculated and computer-modeled for the requirements athand and the corresponding custom-moulded ear-plug unitcustom-fabricated. And again, a particularly suitable way to accomplishthis is to employ the production process first above explained, based onthe additive building principle known from rapid prototyping andcontrolled by the optimized modeling data.

3. Optimized Structural Stability of Custom-Moulded Ear-Plug Units

This chapter serves to introduce novel custom-moulded ear-plugs whichare optimally adapted to the dynamics of the area of application. Forexample, it is a known fact that, due to their essentially uniformdegree of structural stability, conventional custom-moulded ear-plugin-ear devices cannot adapt to the relatively strong dynamic movement ofthe auditory canal for instance during mastication. Similarly, theacoustic conductors for instance between pinnal i.e. external hearingaids and the auditory canal cannot freely follow a dynamic movement ofthe area of application. In the case of in-ear custom-moulded ear-plugs,and with ear protectors, earphones, water-repellent ear plugs etc., thesame problem is encountered, albeit in part to a lesser degree. Mostimportant, some of their intrinsinc functionality such as theirprotective effectiveness are compromised the more an allowance is madefor the aforementioned dynamics of the area of application. Referencecan be made for instance to conventional ear protectors made of anelastically deformable plastic material which, although adapting to thementioned dynamics of the area of application, do so at the expense oftheir acoustic transmission characteristics.

FIG. 15 shows in schematic fashion a longitudinal section of an in-earcustom-moulded ear-plug device, FIG. 16 schematically illustrates partof the cross section of that same custom-moulded ear-plug unit. Thecustom-moulded ear-plug unit, for instance designed to accommodateelectronic components, includes a shell 45 which, sock-shaped, consistsof a thin-walled, elastic material. Where desired, the structuralstability of the skin of the shell, smooth on the outside in the designexample shown, is assured by means of fins or ribs 47 integrated intothe inside of the shell which ribs are of the same material as the skinof the shell.

Depending on the necessary dynamic adaptability of the in-earcustom-moulded ear-plug device for instance to match the dynamics of theauditory canal, and on the requirements in terms of channel locks andfor protecting built-in components as in the case of an in-ear hearingaid, the progression of the wall thickness of the shell skin 45 and thedensity and shape of the ribs 47 are computed in advance and thecustom-moulded ear-plug unit is built on the basis of the computed data.And again, the above-mentioned production method, employing the additivebuild-up process, is eminently suitable for the task. Of course, thedesign of the in-ear custom-moulded ear-plug unit as just explained canwithout question be combined with a venting system as described withreference to FIGS. 7 to 14. In particular, for modifying the degree ofrigidity i.e. flexibility in specific regions of the custom-mouldedear-plug unit the ribs can have varying cross sections which, ifdesirable, may also transition progressively along their longitudinalaxis from one cross section to another.

By way of a perspective illustration, strictly representing one typicalexample, FIG. 17 schematically shows the outer skin 45 with ribs 47, thelatter displaying varying cross-sectional surface dimensions in thelongitudinal direction.

In lieu of or in addition to the targeted wall reinforcement andpredefined bending and torsional characteristics, in short thestructural properties of the in-ear custom-moulded ear-plug unit, theinner ribbing as shown in FIGS. 17 and 18 may be complemented by anouter rib pattern as mentioned further above. To that effect, asindicated in FIGS. 18 and 19, the outer surface of the custom-mouldedear-plug unit 49 is provided with a pattern of ribs 51 which may differregionally in terms of their density, orientation and cross section.

FIG. 19 shows that this approach can be taken with the hollow,cavity-type custom-moulded ear-plugs, but it is equally suitable forcustom-moulded ear-plug units without a cavity, for instance withoutelectronic components, and thus for devices such as ear protectors andwater-blocking ear plugs. The cross section of an custom-mouldedear-plug unit of this type is schematically shown in FIG. 20. In thiscase, the core 53 is made for instance of a highly compressibleabsorption material, surrounded by a contour-shaping skin 55 withribbing 57. The “skin” 55 and the ribbing 57 are produced jointly andintegrally, for which once again the production method first abovedescribed, employing the additive build-up process, offers itself. Towhat extent any such additive build-up process will be implementable anytime soon when applied to a work piece with inhomogeneous materials,remains to be seen. If that turns out to be possible, the road is clear,for instance in the case of the design example per FIG. 20, to alsobuild the filler 53 concurrently with the skin 55 and the ribs 57, layerby sequential layer.

Going back especially to FIGS. 18 and 19, it will be evident that theouter rib profiles can also double as delineators for venting channelsand/or free spaces, as is illustrated in purely schematic fashion by theexample of path P.

Referring back once again to FIG. 20, to the dotted line 57, it isentirely possible, if necessary, to provide the shell skin 55 with aninner rib pattern 57 even when the in-ear custom-moulded ear-plug unitis filled with a filler material and is not intended to accommodateother components such as electronic modules.

Moreover, as indicated by the dotted line 59 in FIG. 20, it is possibleto produce custom-moulded ear-plug units with a cavity for accommodatingmodules such as electronic components which cavity 59 is specificallyshaped to conform to the size and shape of these additional componentsto be installed, while at the same time the space between that cavityand the shell skin 55 is filled for instance with a resilient orsound-absorbing material or, alternatively, the components to beinstalled are embedded in such a material up to the shell skin 55.

The shell skin 55 or, respectively, 45 per FIGS. 15, 16 and 17, may infact be produced from an electrically conductive material, creating atthe same time an electrical shield for internally situated electroniccomponents. Where appropriate, this also applies to the filler material53 per FIG. 20.

FIGS. 15 to 20 illustrate an example of an in-ear custom-mouldedear-plug device whose shell is reinforced with inner and/or outer ribprofiles, allowing the structure to be exceptionally light-weight andcustomizable. Obviously, where necessary, this type of structure canalso be employed in outer-ear custom-moulded ear-plug units.

FIG. 21 shows another design variation of an in-ear custom-mouldedear-plug unit with a specific pliable and, respectively, compressiblesection. This is accomplished in that the shell 61 of an custom-mouldedear-plug unit, and in particular the shell of an in-ear hearing aid, isprovided in one or more predefined areas with a corrugated orbellows-like section 63 which is flexibly expandable or compressible tothe necessary extent. Although FIG. 21 illustrates this concept inconjunction with the shell of an in-ear custom-moulded ear-plug device,that concept, where necessary, is entirely implementable in a pinnalcustom-moulded ear-plug design as well. Again, the preferred productionmethod is as first above described.

In the case of this design example as well it is possible, as explainedin reference to FIG. 20, to fill the inner space of the custom-mouldedear-plug unit with the proper filler material for the purpose intended,or to embed integrated modules in such a filler material, thus obtainingimproved stability of the device as well as better acoustic properties.

4. Modular Housing and Build-Ins

A problem especially with in-ear hearing aids consists in the fact thatthe shape of the area of application, i.e. the auditory canal, changesprogressively. This is obviously true in the case of youngsters growingup, but even the ear canal of adults changes, often considerably, andmostly in a constrictive sense (e.g. the co-called diver's ear).

Conventional in-ear hearing aids, even where their components couldotherwise be expected to be retainable for extended periods in aperson's life, perhaps requiring only a readjustment of the transmissioncharacteristics of the hearing aid in adaptation to the changed auditoryconditions, thus pose a problem in that an all-new hearing aid needs tobe designed repeatedly merely because the previous ones no longer fitproperly into the ear canal.

This can already be improved alone by means of the measures explained inthe above chapter 3) due to the fact that they permit an automaticadaptation of the shape of the custom-moulded ear-plug unit to thechanging area of application. The following will describe additionalmeasures especially for in-ear custom-moulded ear-plug devices. Itshould be pointed out, however, that for outer-ear custom-mouldedear-plugs as well, such as pinnal hearing aids, it becomes possible toreplace the “housing”, and not only when that is necessary for reasonsof wearing-comfort but also, if desired, for instance for changing theaesthetic appearance of such an outer-ear hearing aid.

FIG. 22 shows schematically the longitudinal section of an in-earcustom-moulded ear-plug unit 65, whose inner space 67 conformsessentially to the shape of the electronic module 69, schematicallyillustrated in FIG. 23, that it must accommodate. The custom-mouldedear-plug unit 65 consists of a rubber-like elastic material and, asshown in FIG. 23, can be slipped over the electronic module 69. Theinner space 67 is so contoured that it matches the shape of any moduleto be accommodated which is thus held in place by and in thecustom-moulded ear-plug unit 65. In this fashion it is easily possibleto equip one and the same electronic module 69 with differentcustom-moulded ear-plug units 65, thus permitting an adaptation to thechanging shape of the auditory canal for instance of a growing child.Thus, for all practical purposes, the custom-moulded ear-plug unit usedfor the in-ear hearing aid becomes a replaceable one-way accessory. Thecustom-moulded ear-plug unit 65 can be easily replaced not only tocompensate for changes in the area of application, that being the earcanal, but also when the unit is soiled. This concept may even proveuseful, for instance in the case of an ear infection, for introducingmedication which could be applied on the outside of the custom-mouldedear-plug unit, or in any event for inserting sterilized custom-mouldedear-plug units at regular time intervals.

The concept illustrated in FIGS. 22 and 23 is, of course, combinablewith those presented in chapters 2) and 3), and the custom-mouldedear-plug unit 65 is preferably fabricated by the production methodexplained in chapter 1), which permits the formation of the most complexinternal configurations for the tolerance- and vibration-freeaccommodation of the module 69.

As can be seen in FIGS. 22 and 23, the phase plate 1 with whichconventional in-ear hearing aids are equipped, is incorporated as anintegral part for instance of the module mount. The same applies toother mounts and retaining cavities for electronic components of thehearing aid. If the incremental layer-by-layer build-up processexplained in chapter 1) is applied following the dotted line in FIG. 22in the direction of the arrow AB, it should be altogether possible tofabricate the custom-moulded ear-plug unit in the progressive build-updirection AB in accordance with the requirements of each area and from avariety of materials. This also applies to the custom-moulded ear-plugdevices discussed in chapters 2) and 3) and to those described in thefollowing chapters 5), 6) and 7). In reference to the example per FIG.22, it is thus entirely possible to fabricate section 65 _(a) from arubber-like elastic material and the port section 65 _(b) from a morerigid material.

Depicted in FIG. 24 is another design version of an custom-mouldedear-plug unit, again as an example of an in-ear hearing aid whichpermits the simple, rapid exchange of the internal, built-in components.It is recommended that for any such in-ear custom-moulded ear-plug unitwith built-in components, the shell be produced in several assemblablesections as shown in FIG. 24. By means of quick-connect closures such ascatch pawls, detents or even bayonet-type junctions it is possible toquickly separate the housing sections 73 a and 73 b of the in-earcustom-moulded ear-plug unit, remove the internal modules such aselectronic components and reinstall these in a new shell, perhaps onewith a modified outer contour or into an altogether different shell, asmay be necessary for instance for cleaning purposes, sterilerequirements etc. In cases where the used shells must be disposed of, itis entirely possible to configure the shell sections in a way that theycan be opened only in a destructive fashion, rendering them nonreusable,for instance by means of locking elements such as pawls which areinaccessible from the outside, so that it is necessary to cut the shellopen for disposal.

Of course, this design version can on its part be combined with thevariants described above and those yet to be described below.

5. Integration of Acoustic Conductors in Custom-Moulded Ear-Plug Devicesor their Shells

The input and, respectively, output ends of acoustoelectric inputconverters or electroacoustic output converters in outer-ear as well asin-ear hearing aids are customarily coupled to the auditory environmentby way of discrete, separately assembled acoustic conductors in the formof tubular structures, or, especially for acoustoelectric inputconverters, their receiving surface is positioned in the immediatevicinity of the hearing-aid surface, possibly separated from theenvironment by only small spaces and protective provisions.

The design of hearing aids of that type involves relatively severerestrictions as to where the converter proper and where on the hearingaid the actual interface to the outside world must be positioned. Itwould be highly desirable to have maximum design latitude in theplacement of the interface to the environment and the positioning of theconverters within the hearing aid.

This is entirely feasible in that the acoustic conductors concerned,extending on the input side from acoustoelectric converters and on theoutput side from electroacoustic converters, are integrated directlyinto the custom-moulded ear-plug unit or the wall of the respectivecustom-moulded ear-plug shell.

That is schematically illustrated in FIG. 25. A converter module 75 isprovided with an acoustic input or output 77. Integrated into the shell79 of the custom-moulded ear-plug unit of an in-ear or pinnal hearingaid or an earphone is an acoustic conductor 81 which, at least in partas shown in FIG. 25, extends within the wall of the custom-mouldedear-plug shell 79; Preferably, acoustic stub connectors or line sections83 are employed for tuning the corresponding acoustic impedance of theacoustic conductor 81. With a view to outer-ear hearing aids, thisconcept makes it possible to provide input openings 85 wherever desired,in an offset arrangement along the hearing aid, and to couple these viathe acoustic conductors 89, integrated into the custom-moulded ear-plugunit or its shell 87, to the appropriate acoustoelectric converters 91essentially regardless of where in the hearing aid these converters 91are located. As an example only, shown in FIG. 26, two converters arecentrally positioned and their inputs are connected to the desiredreceiving ports 85 via the above-mentioned acoustic conductor 89. Itwill be evident from FIGS. 25 and 26 and from the discussion in chapter2) of the innovative venting systems that it is entirely possible forthe venting channels to double as acoustic conductors, especially if, asschematically indicated in FIG. 25, acoustic adapters 83 are used fordefining specific acoustic impedance parameters.

6. Marking of Custom-Moulded Ear-Plug Units

When custom-moulded ear-plug devices and especially in-ear hearing aidsare manufactured, they are customized for each individual wearer. Itwould therefore be highly desirable to label each such manufacturedcustom-moulded ear-plug unit, especially each in-ear custom-mouldedear-plug device and most particularly each in-ear hearing aid. Hence, itis recommended that each custom-moulded ear-plug unit or its shell beprovided with a recessed or raised labeling area for individualizedmarkings that may include, in addition to the name of the individualbuyer, such information as the manufacturer, product serial number, leftor right ear application, etc. Most preferably, such labeling isproduced during the fabrication of the custom-moulded ear-plug unit bymeans of the ablation process referred to under 1) above. This ensuresthat there can be no mix-up with the custom-moulded ear-plug devices.This is particularly important in the subsequent, possibly automatedassembly process involving additional modules, for instance in theassembly of in-ear hearing aids.

Of course, this step can be combined with any one or several of theprocedures described in chapters 2) to 5) above.

7. Optimization of Custom-Moulded Ear-Plug Devices Relative to theDynamics of the Area of Application

For the fitting of custom-moulded ear-plug devices intended for in-earapplication, such as in-ear hearing aids, current practice involves thetaking of an impression, for instance in silicone, of the auditorycanal. Considering the relatively substantial dynamics of movement ofthe ear canal, for instance during mastication, it becomes obvious thatsuch an impression, a snapshot as it were, can hardly produce a fit ofthe in-ear custom-moulded ear-plug unit that is entirely satisfactory ineveryday use. Therefore, according to the new method as illustrated bythe simplified functional/signal-flow diagram in FIG. 27, measurementsare taken at several points of statistical dynamic movement in thedynamic application area, represented by the block 93, i.e. the dynamicmovement of the area of application is recorded, frame by frame. Thedata sets thus obtained are stored in a memory module 95. Withconventional impression-based methodology as well, this approach can beimplemented by taking impressions of the area of application at two ormore points representative of the actual dynamic movement.

These impressions are then scanned and the corresponding digital datasets are stored in the memory 95. It would also be possible to usex-rays for acquiring the dynamic data of the application area.

Accordingly, depending on the intended degree of precision, a number of“frames” or, for all practical purposes, a “film strip” of the movementpattern in the application area of interest is recorded. The datarecorded and stored in the memory module 95 are then fed into a computer97. The output end of the computer 97 controls the custom-mouldedear-plug production process 99. If, as is still common practice, thein-ear custom-moulded ear-plugs produced include a relatively hardshell, the computer 97 will use the dynamic data stored in the memory95, as well as perhaps other production parameters as schematicallyindicated at point K, and calculate these for the best fit of thecustom-moulded ear-plug unit so as to assure optimal wearing comfort indaily use without compromising functionality. When the custom-mouldedear-plug unit is fabricated following the principle explained in chapter3), the computer 97 will determine which sections of the custom-mouldedear-plug unit must have what characteristics in terms of flexibility,pliability, compressibility etc. As mentioned above, the output end ofthe computer 97 controls the production process 99, and preferably theproduction process referred to in chapter 1) as the technique of choice.

1) A method of manufacturing an ear plug device to be introduced intothe ear canal of an individual comprising computer modelling acousticalproperties of at least one venting void to be formed by at least oneventing groove in an outer surface of said device and the surface ofsaid canal, said outer surface comprising a part to be in contact withthe surface of said canal and manufacturing said hearing device with agroove in said outer surface in dependency of said computer modelling.2) The method of claim 1, said modelling comprising modelling saidacoustical properties in dependency of length of said at east one void.3) The method of claim 2, said modelling comprising selecting saidlength to be longer than a length extent of said device along saidcanal. 4) The method of claim 1, said modelling comprising modellingsaid acoustical properties in dependency of at least one of shape and ofvariation of shape of cross sectional area of said void along said void.5) The method of claim 4, said modelling comprising modelling saidacoustical properties in dependency of length of said at east one void.6) The method of claim 5, said modelling comprising selecting saidlength to be longer than a length extent of said device along saidcanal. 7) The method of claim 4, wherein said at least one of shape andof shape variation comprises at least one of at least in part square, atleast in part rectangular, at least in part elliptical, at least in partcircular, at least in part triangular. 8) The method of claim 7, saidmodelling comprising modelling said acoustical properties in dependencyof length of said at east one void. 9) The method of claim 8, saidmodelling comprising selecting said length to be longer than a lengthextent of said device along said canal. 10) The method of claim 4,wherein said shape variation comprises variation between at least two ofat least in part square, at least in part rectangular, at least in partelliptical, at least in part circular, at least in part triangular. 11)The method of claim 10, said modelling comprising modelling saidacoustical properties in dependency of length of said at east one void.12) The method of claim 11, said modelling comprising selecting saidlength to be longer than a length extent of said device along saidcanal. 13) The method of one of claims 1 to 12, said modellingcomprising modelling in dependency of the cross sections of said void.14) The method of one of claims 1 to 12, said modelling being based onacoustic impedance. 15) The method of claim 13, said modelling beingbased on acoustic impedance. 16) The method of one of claims 1 to 12,said modelling comprising modelling in dependency of application area ofsaid device in the ear canal. 17) The method of claim 13, said modellingcomprising modelling in dependency of application area of said device inthe ear canal. 18) The method of claim 14, said modelling comprisingmodelling in dependency of application area of said device in the earcanal. 19) The method of claim 15, said modelling comprising modellingin dependency of application area of said device in the ear canal. 20)The method of one of claims 1 to 12, wherein said outer surface of saiddevice consists of a first part defining for said at least one grooveand a second part for contacting said surface of said canal. 21) Themethod of claim 13, wherein said outer surface of said device consistsof a first part defining for said at least one groove and a second partfor contacting said surface of said canal. 22) The method of claim 14,wherein said outer surface of said device consists of a first partdefining for said at least one groove and a second part for contactingsaid surface of said canal. 23) The method of claim 15, wherein saidouter surface of said device consists of a first part defining for saidat least one groove and a second part for contacting said surface ofsaid canal. 24) The method of claim 16, wherein said outer surface ofsaid device consists of a first part defining for said at least onegroove and a second part for contacting said surface of said canal. 25)The method of claim 17, wherein said outer surface of said deviceconsists of a first part defining for said at least one groove and asecond part for contacting said surface of said canal. 26) The method ofclaim 18, wherein said outer surface of said device consists of a firstpart defining for said at least one groove and a second part forcontacting said surface of said canal. 27) The method of claim 19,wherein said outer surface of said device consists of a first partdefining for said at least one groove and a second part for contactingsaid surface of said canal. 28) The method of one of claims 1 to 12,wherein said modelling comprises modelling in dependency of aprogressive change of the cross sectional shape of said void. 29) Themethod of claim 13, wherein said modelling comprises modelling independency of a progressive change of the cross sectional shape of saidvoid. 30) The method of claim 14, wherein said modelling comprisesmodelling in dependency of a progressive change of the cross sectionalshape of said void. 31) The method of claim 15, wherein said modellingcomprises modelling in dependency of a progressive change of the crosssectional shape of said void. 32) The method of claim 16, wherein saidmodelling comprises modelling in dependency of a progressive change ofthe cross sectional shape of said void. 33) The method of claim 17,wherein said modelling comprises modelling in dependency of aprogressive change of the cross sectional shape of said void. 34) Themethod of claim 18, wherein said modelling comprises modelling independency of a progressive change of the cross sectional shape of saidvoid. 35) The method of claim 19, wherein said modelling comprisesmodelling in dependency of a progressive change of the cross sectionalshape of said void. 36) The method of claim 20, wherein said modellingcomprises modelling in dependency of a progressive change of the crosssectional shape of said void. 37) The method of claim 21, wherein saidmodelling comprises modelling in dependency of a progressive change ofthe cross sectional shape of said void. 38) The method of claim 22,wherein said modelling comprises modelling in dependency of aprogressive change of the cross sectional shape of said void. 39) Themethod of claim 23, wherein said modelling comprises modelling independency of a progressive change of the cross sectional shape of saidvoid. 40) The method of claim 24, wherein said modelling comprisesmodelling in dependency of a progressive change of the cross sectionalshape of said void. 41) The method of claim 25, wherein said modellingcomprises modelling in dependency of a progressive change of the crosssectional shape of said void. 42) The method of claim 26, wherein saidmodelling comprises modelling in dependency of a progressive change ofthe cross sectional shape of said void. 43) The method of claim 27,wherein said modelling comprises modelling in dependency of aprogressive change of the cross sectional shape of said void.